Influence of Solvent Polarity and Hydrogen Bonding on the Electronic Transition of Coumarin 120: A TDDFT Study

Abstract

The characteristics of the electronic transition energy of Coumarin 120 (C120) and its H-bonded complexes in various solvents have been examined by time-dependent density functional theory (TDDFT) in combination with a polarizable continuum solvent model (PCM). Molecular structures of C120 and its H-bonded complexes are optimized with the B3LYP method in PCM solution, and the dihedral angle H14-N13-C7-H15 is dependent on solvent polarity and the type of H-bond. A linear correlation of the absorption maximum of C120 with the solvent polarity function is revealed with the PCM model for all solvents except DMSO. The experimental absorption maximum of C120 in nine solvents is well described by a PCM-TDDFT scheme augmented with explicit inclusion of a few H-bonded solvent molecules, and quantitative agreement between our calculated results and experimental measurements is obtained with an average error of less than 2 nm. H-bonding at three different sites shifts the absorption wavelength of C120 either to the blue or to the red, that is, a significant role is played by solvent molecules in the first solvation shell in determining the electronic transition energy of C120. The dependence on the H-bonding site and solvent polarity is examined by using the Kamlet-Taft equation for solvatochromism.

Time‐dependent density functional theory study on the absorption spectrum of Coumarin 102 and its hydrogen‐bonded complexes

“…The calculated absorption wavelength for the C120 with four water molecules including the type A HB is in excellent agreement with the experiment measurement. 12 The amino group of C102 is similar to the amino group of Courmain 1 and the absorption spectrum of the C102 is experimentally observed to be red-shifted in water solvent compared with in ethanol and methanol solvents. 13,14 So, the type A HB should be avoided for the C102 in water and other solvents.…”

“…This method has been widely used in recent years. [8][9][10][11][12] The general form of the Kamlet-Taft equation is…”

Theoretical study on the photodegradation reaction of deca-BDE in THF in the presence of furan

“…The photodegradation reaction of BDE209 in the THF solvent in the presence of furan is investigated using the timedependent [32][33][34] density functional theory (TD-DFT) with the M06 functional [35], which has been shown to be successful in describing the non-covalent interactions, dissociation processes, and excitation properties of some aromatic molecules [36][37][38][39][40][41][42][43][44][45]. The polarizable continuum (PCM) model [46] is employed to evaluate the bulk solvent effects of THF throughout the calculations.…”

DFT/TD-DFT study of the structural and spectral properties of two forms of Rhodamine B

“…This method has been used in the studies of isomerization 16,17 and spectral properties. 21,22,32,33 3. Results and Discussions…”

“…The hydrogen bond e®ect on absorption spectra of zwitterion and cation is investigated using explicit solvent model, 21,22,32,33 where molecule involved in hydrogen bond interaction is explicitly treated using full electronic structure calculations and bulk e®ect of solvent is simulated by PCM method. The possible hydrogen bond interactions of cation with water molecule are illustrated in Fig.…”